Coated tools known to-date include cutting tools in which a single or a plurality of titanium carbide layers, titanium nitride layers, titanium carbonitride layers, aluminum oxide layers, and titanium aluminum nitride layers are formed on the surface of a substrate such as cemented carbide alloy, cermet, or ceramic.
In such cutting tools, opportunities for using heavy interrupted machining or the like, in which high impact is applied to the cutting edge, have increased with the recent increased performance of cut processing, and improvements in defect resistance and wear resistance have come to be demanded in order to suppress peeling of the coating layer or chipping due to the high impact applied to the coating layer.
As technology that improves defect resistance in the above cutting tools, Patent Document 1 discloses technology by which a compact aluminum oxide layer having high defect resistance can be formed by appropriately adjusting the particle size and layer thickness of the aluminum oxide layer and by setting the texture coefficient (orientation factor) in the (012) face to not less than 1.3. Patent Document 2 discloses technology by which defect resistance of an aluminum oxide layer can be improved by enabling easy release of residual stress in the aluminum oxide layer by setting the texture coefficient in the (012) face of the aluminum oxide layer to not less than 2.5.
As technology that improves wear resistance in the above cutting tool, Patent Document 3 discloses technology by which strength and toughness of a coating film can be improved by forming an aluminum oxide layer positioned directly above an intermediate layer so as to result in lamination of unit layers of two or more layers exhibiting different X-ray diffraction patterns.
Patent Document 4 discloses a cutting tool in which the orientation factor of the (006) face of an aluminum oxide layer is not less than a high 1.8, and the peak intensity ratio I(104)/I(110) of the (104) face to the (110) face is controlled within a prescribed range. Additionally, Patent Document 5 discloses a cutting tool in which the peak intensity ratio I(104)/I(012) of the (104) face to the (012) face is greater in a second face than in a first face on the bottom side of an aluminum oxide layer.